Search Documents

By G. T. Adel, J. D. Miller, C. L. Lin

Washability analysis determines the maximum separation efficiency that can be achieved in the operation of coal preparation plants. Unfortunately, there are no on-line techniques for determining this most fundamental information. It now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. This paper presents the results for the development of a CT-based, on-line coal washability analyzer. The development of appropriate hardware and software necessary to adapt a CT analyzer for use in determining coal washability is discussed. Testing of the analyzer using well-characterized coal samples is presented.

Jan 1, 2000

By G. G. Gold

A leach pad’s fluid flow characteristics greatly affect the recovery of metals from heap leaching. However, because there are other factors such as particle size distribution, application rate and method, and chemical reactions to consider, mining companies often overlook potential problems associated with fluid flow until it is too late. In an effort to better understand the dynamics of fluid flow in leach pads, a series of experiments were preformed using temperature probes. A model leach pad was set up using a particle size distribution, fluid application rate, and application method common to modern leaching methods. Variable water temperatures were applied in succession and data gathered from the three dimensional grid of temperature probes built in to the model. Current work is analyzing these data along with visual observations of the model, computer simulations, past mining experiences, and other related research, in an attempt to develop a low cost test that could be performed prior to large scale leaching to determine the fluid flow characteristics of a particular ore. This paper will summarize the work and findings to this point as well as suggest areas of additional related research.

Jan 1, 2004

By Christa Overby

As part of the City of Portland, Oregon?s East Side Combined Sewer Overflow Tunnel Project, nine separate 2,130 mm (84-inch) diameter reinforced concrete pipe microtunnel drives totaling approximately 2,380 m (7,808 ft) are being constructed to divert flows from several of the existing outfalls to the main tunnel. The drives were constructed in challenging ground conditions that include soft soils under the ground-water table, large amounts of wood and metal debris, and close proximity to sensitive structures. While all of the drives will be addressed, the focus of the paper will be on the 931 m (3,055 ft) continuous drive connecting Outfall 46, currently the longest microtunnel driven in North America.

By M. Fustic, A. H. Paul

The geology of the Muskeg River Oil Sands Mine is described to demonstrate how geologic modeling aided in resource evaluation and material characterization during the feasibility and construction stages. Bitumen is hosted in the clastic sediments of the Cretaceous McMurray Formation which is informally divided into members representing the fluvial, estuarine and marine environments of this transgressive sequence. Lithofacies mapping of drill core provides further detail to classify materials as resource type, for extraction suitability and for construction suitability. Geologic interpretation provides tools for the engineers to produce effective mine plans and for the operators to execute them during mine development.

Jan 1, 2002

By Wolfgang Roth

In 1990, a residential area above the North Outfall Sewer (NOS) tunnel constructed in 1924, experienced subsidence. After sewage was diverted into the North Outfall Replacement Sewer (NORS), soil probing from within the tunnel was conducted, soil-improvement options were developed, and a preferred grouting scheme was analyzed by numerical modeling to evaluate the stability of the 80-year+ old tunnel liner under grouting-induced loading conditions. This paper discusses the initial field investigation and the development and analysis of a grouting scheme originally intended to be implemented before relining of the tunnel. The scheme was later modified, and the new liner was installed before the final probing and grouting work was done.

Jan 1, 2008

By W. G. Pariseau

This contribution focuses on the role of stress analysis for mine planning and the selection of suitable computer programs for the task with special emphasis on coal mine pillars. In this regard, barrier pillars that defend a set of five main entries at the Crandall Canyon coal mine in central Utah were formed during extensive longwall mining north and south of these main entries. Numerical analysis for ground control guided the mine planning and permitting. Retreat mining of pillars led to disastrous events August 6 and 16, 2007, with the loss of nine lives. A most difficult lesson taught by the Crandall Canyon tragedy is the need for education in the selection and use of computer programs for pillar design. Much of this contribution is taken from a report prepared for the Mine Safety and Health Administration (Gates, et al, 2008). Details appear in Appendix Q of the report (Pariseau, 2008). The Crandall Canyon mine is about 16 miles west of Huntington, Utah, in the Wasatch Plateau coal field. Geology of the Wasatch Plateau is described by Doelling (1972) as gently dipping Cretaceous sandstones, mudstones, coal seams, and shales. Joint systems are present in strata above and below coal seams where cleat systems are present as described by Hucka (1991). Several major fault systems transect the field and form grabens with 450- 760 m of drop. One such structure is Joes Valley fault that crosses the Crandall Canyon mine. Mines in the Wasatch Plateau are generally developed from outcrops in steep canyon walls. Overburden increases rapidly as mining progresses into the plateau; mining depth varies with topography between 450 and 600 m in the region of interest. A stratigraphic column derived from a borehole into the mine is shown in Figure 1. There are 11 layers in the column.

Jan 1, 2011

By L. A. Puchkov

Problems of how to use artificial intelligence (AI) methods and expert systems (ES) to control complex industrial projects have lately become significant in practical terms. Mining ventilation systems undoubtedly belong to complex multi dimensional objects of control with stochastic nonstationary and nonlinear processes. Formal models based on automated ventilation control, do require awkward algorithmic solutions, moreover, a number of tasks become the operator's headache, and the quality of their solution depends on his experience and intuition. These tasks include: - identifying pre-accidental situations and determining their causes; - making well-grounded decisions with regard to changing ventilation regimes, forecast of mining operations taken account of; - controlling ventilation systems in emergency situations, e.g. when in accident, etc. It is in this context that we have for a number of years been investigating how to practically use AI methods for operative control in dynamic aero-and-gas mining processes, one of our research directions being devoted to working out a consulting programme for the ventilation system operator. Our researching and modeling problem was identification of aero-and-gas situation in different parts of ventilation network and its interpretation in order to determine possible causes for gas regime changing and unexpected consequences. We would single out the following stages in this task: I. Operative information procession coming to the data base from the sensors and analysis of hypothetical versions (using the associative rules base) with regard to factors which have caused significant parameter fluctuations (e.g. C%(t), H(t), Q(t) etc.)., 2. Selection of hypotheses in the knowledge base and forming conclusions in accordance with reliability scale. 3. Clarifying the obtained conclusions in dialogue with the operator. 4. Correcting the associative rules base.

Jan 1, 1992

By Robin J. Batterham

We still need to innovate, but it is getting harder. The real price of metals is declining, return on shareholder value is lower than other industries, and there is a shorter-term focus on staying viable in a capital-intensive industry where timeframes for implementation of new technologies can be long (+I5 years). In this environment, the levels of R&D spent by major minerals companies are remaining steady at around 0.2%-0.5% of revenue. This is not large and to remain viable in the future, we need to be smarter about the way in which we do R&D. The mining industry is a knowledge-based industry. Driving down the cost curve demands innovation, which demands knowledge. To be smarter and more effective in our approach to innovation, a new paradigm is required Generating, capturing and using knowledge has evolved from Mode 1 (discipline based and clear distinction between basic and applied research) to Mode 2 (multidisciplinary, team-based approached with flow between basic and applied activities). Mode 2 is now seen to be much more efficient and to deliver better appropriability (Tegart 2003). To survive, we need to innovate, and the best way to do this is collaboratively. Some examples and pointers for the future will be given in this paper. THE CURRENT SITUATION The Rand report and other recent studies have painted a grim outlook for the mining industry. The real price of metals continues to decline (Figure 1) and profit margins remain thin. This is reflected in shareholder returnwhich are well below other industries (Figure 2)-and current management strategies-which reflect something of a "survival mode." The current focus for most mining companies is on short-term, incremental gains

Jan 1, 2004

By I. J. Duckworth

During the last twenty years computers have be-come widely used to assist with the simulation and design of large scale, primary ventilation systems. However, to date there are few computer programs available to help with the modeling of auxiliary ventilation in dead-end headings or tunnels. This paper presents the results of the first year of a research and programming study dedicated to the development of a user-friendly duct simulation tool. Included is a literature review that summarises publications on duct leakage and resistance, on previous programs developed for the simulation of airflow in ducts, and case studies on extended ductlines in mines and tunnels. The methodology behind the development of Ductsim, a Windows based simulation program is presented.

Jan 1, 2000

Steven F. Leer, president and chief executive officer of Arch Coal Inc. will be the master of ceremonies for the 12th Annual National Mining Hall of Fame Induction Banquet. The black-tie (optional) affair will be held at the Adam’s Mark Hotel on Sunday, Oct. 10 in St. Louis, MO. Six legendary leaders will be inducted at the ceremony. They will join 145 mining greats previously honored in the annual ceremonies. R. Joe Wagner, vice president for exploration and chief geologist of The Doe Run Co., St. Louis, will be the evening’s keynote speaker. His father, Richard Edwin Wagner (1898-1979), was inducted into the National Mining Hall of Fame in 1998 at the banquet in Phoenix, AZ.

Jan 1, 1999

By Rei Arai, Yuta Yamamoto, Tetsuo Yamazaki, Naoki Nakatani

"Methane hydrate is of interest as an alternative energy resource in Japan and the R&D program has been ongoing for ten years (MH21: http://www.mh21japan.gr.jp/english/). Rare-earth element-rich deep-sea mud (REE Mud) is also of interest as an alternative resource in Japan and an exploration program has been launched in 2013.For methane recovery from the hydrate, a depressurization method pumps up water in a production well and has been successfully applied in field production tests (MH21: http://www.mh21japan.gr.jp/english/). However, micro-bubbles, which appear in the hydrate dissociation and water recovery processes may present an environmental issue. It may stick on clay and silt particles that accompany the recovered water, and may disturb settling of the particles in the water separation tank. For exploitation of REE Mud, an air-lift system has been proposed in the feasibility study (Abe et al., 2012). The same micro-bubble issue is expected during the air, water, and mud particle separation processes. In this research, the authors conducted a preliminary tank experiment for clarifying the effect of micro-bubbles on settling behavior of fine kaolinite particles. The behavior was continuously recorded by a still camera and the images were analyzed by the gray scale intensity. From the results the authors found a suspension effect for the settling of fine particles as the result of micro-bubbles. The effect should be studied in detail for preventing some serious environmental impacts during deep-sea mining."

Sep 1, 2014

By L. M. English, Y. J. Wang

When plotted as head vs. volume, fan curves start high and decrease in head with increasing volume while mine head curves start low and rise with increasing volume. Their intersection is the system operating point. But wait a minute: Isn't head loss a negative number, a debit? And isn't fan head an energy addition, a credit? This, as every ventilation instructor knows, is often a stumbling block to student or audience comprehension. It is possible to use the intuitively correct curves - pressure losses as negative values and energy additions as positive values-and still obtain the correct operating point: adding the two curves produces a third curve that intersects the x-axis at the operating point, the point at which the fan energy input exactly matches air circulation energy loss. Using this technique also makes it easier to account for outside influences on the system, such as natural ventilating pressure; with the standard approach it is quite easy to add or subtract such influences to the wrong curve. This approach can be extended to the graphical solution of any series/parallel circuit or ventilation network. The results are the same, and the approach is logically consistent and less confusing.

Feb 24, 1997

By A. Nieto

A dump edge and vehicle proximity warning system is being developed at the Colorado School of Mines using GPS and wireless local area networks to improve the safety of off-highway trucks in open pit mines. After two years of research, software development, and testing in the laboratory, field tests are currently being carried out at operating limestone quarries and open pit mining operations to evaluate the effectiveness of the system under rugged operating conditions. This paper describes the progress made on this NIOSH-funded project and discuss, tests carried out recently, at the Morenci open pit copper mine in Arizona.

Jan 1, 2002

The Forestry Reclamation Approach (FRA) specifies that the upper 1.22 m of material on the reclaimed surface should be left as uncompacted as possible to facilitate tree root growth. One of the main concerns about applying the FRA to steep slopes is that the upper 1.22 m of material could cause the reclaimed slopes to be unstable. Successful application of FRA on flat and rolling surfaces precipitated this investigation. Details of a field investigation conducted at a steep-slope mine are available in an earlier publication (Kumar and Sweigard, 2011). A total of 70 survey monuments were driven into the slope in a regular pattern to monitor slope movement. Quarterly surveys of the monuments were done to quantify any type of mass movement either horizontally or vertically. The methodology proposed for slope movement was verified using numerical models. Analytical models based on limit equilibrium technique and numerical models based on the finite element method were developed for slope stability analysis. The limit equilibrium analysis was done using Geo-Slope software following the Simplified Bishop Method. The finite element (FEM) numerical model was developed using the Plaxis computer program following the strength reduction technique. Two kinds of slope stability analysis were performed: first with the top 1.22 m of loose material and second without top loose material. Finally, the field investigation results were compared with stability analysis results. Both of these approaches showed that application of the FRA on steep slopes is not causing any significant instability problems that would not exist otherwise for overly steepened slopes. Keywords: Forestry reclamation approach, steep slope, slope movement, factor of safety

Feb 27, 2013

By Jimmy Thompson

The Santa Clara Valley Transportation Authority is designing the Silicon Valley Rapid Transit Project in San Jose, California. The project includes 6.9 km (4.3 miles) of twin-bored tunnels to be constructed through downtown San Jose using two earth pressure balance machines (EPBMs). This paper begins with a project description and update of the project status followed by a description of the relationship between anticipated ground conditions and EPBM requirements. Topics addressed include soil conditioning, abrasion resistance, annulus grouting, face pressure estimation, additional pressure control devices and control measures to limit over-excavation and settlement.

Jan 1, 2008

By Michael Cruickshank

Bob Woolsey was born in 1936 in the state of Georgia and grew up to be a man of great integrity, vitality, wisdom and charm, totally neutral on matters of race, gender, and religion. A true Southern Gentleman in every sense of the word. His passing on July 9, 2008, the victim of an automobile collision, left an empty space in the hearts of his family, and his many friends and colleagues throughout the globe. The posthumous award of the Moore Medal of the International Marine Minerals Society, to Dr. J. Robert Woolsey for Excellence in the Development of Marine Minerals, is a well deserved tribute to this man who spent the last 30 years of his professional career heavily involved in research and development of marine minerals on an international basis. He first came to my attention in Burma in 1979 where, as a newly appointed technical advisor to the United Nations Development Program Offshore Exploration for Tin, I had to fill the shoes of an almost legendary figure "Dr. Bob", who accompanied by his wife Maxine had spent the previous two years initiating the program. Bob had planned to completion the construction in Singapore of a unique drilling vessel the RV Sea Drill, a spud anchored, twin-hulled barge, mounted with a Becker Drill, and designed for sampling alluvial tin deposits in the coastal waters of the Mergui Archipelago in the Andaman Sea, off Tenasserim. He had also designed and built, with the help of his side -kick Bruce Jernigan, a barge mounted dressing plant for reducing and concentrating the drill samples. The adventures of Dr. Bob in transporting the equipment to the drilling site in monsoon weather and the transfer of the drill barge from the Malaysian port of Ranong across the strait to Victoria Point in Burma with a mutinous crew will remain in the hearts and minds of his Burmese colleagues for many a long year. On his return to the States he joined, in 1980, the faculty of the University of Mississippi (UM) as assistant Professor of Geology and Geological Engineering. His prior experience in private industry and the United Nations had focused on marine mineral resources and related environmental engineering projects in Africa, South America, the Mediterranean, the South Pacific as well as south east Asia, working with dredges, mining for alluvial tin, gold, diamonds and industrial minerals. He continued to work in the area of marine minerals at UM, making a name for himself as Director of the Mississippi Mineral Resources Institute (MMRI).

Jan 1, 2008

By Ian Farmer, Nigel Glossop, Philip Garritty

Performance of tunnel boring machines - usually expressed in terms of penetration per revolution - is determined by relations between machine thrust and torque, head diameter and rock strength. It can be shown that for a given machine power and head diameter there is only one rock strength at which the machine performs optimally. In weaker rocks the available torque limits performance and in stronger rocks, the available thrust. Performance data shows that, historically, machines have been designed to cut weaker rocks. Optimization of thrust is required to improve performance in stronger rocks.

Jan 1, 1987

By A. B. Cecala

Enclosed cabs have been used for many years to isolate workers on mobile equipment in the mining industry for health and safety reasons. These enclosed cabs create a microenvironment for workers where they can be either more protected or more vulnerable to contaminants. Over the past decade, the National Institute for Occupational Safety and Health (NIOSH) has performed substantial research efforts to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment. In these efforts, NIOSH has partnered with mining companies, original equipment manufacturers (OEMs), and manufacturers of filtrations and pressurizations systems in a synergistic effort to reduce respirable dust and improve the air quality inside these enclosed cabs. Various field studies over this time have shown an array of results ranging from very minor to very significant reductions (protection factor: 3 ? 89) in respirable dust levels inside these enclosed cabs. In addition to and concurrent to the field work, NIOSH also performed a comprehensive laboratory study to evaluate all the factors involved in cab filtration and pressurization systems and identified those factors that were most significant for an effective system. From this comprehensive research effort, the key components for an effective filtration and pressurization system have been identified in an effort to provide the best air quality, thus minimizing the respirable dust exposure, to equipment operators inside of enclosed cabs of mobile mining equipment.

Feb 27, 2013

By Clay Haynes

While the Kansas River Tunnel is a relatively short, small diameter tunnel, the shaft excavation methods implemented were long and large on innovation and use of reverse circulation drilling equipment. ATS Drilling, L.P. used mechanical excavation techniques for both soil and rock segments of the 42.7 m (140 feet) and 38.1 m (125 feet) deep shafts that were 2.9 m (9.5 feet) and 4.1m (13.5 feet) diameter, respectively.

By C. Green, J. Uhrie, C. Filippone, A. Guzman

A central aspect of heap leach management and recovery optimization is solution control. Insofar as each heap is unique in physical and metallurgical properties, it is essential to understand the hydraulic parameters that control the migration of solution on a case-by-case basis. Water Management Consultants, as part of an ongoing research effort for Phelps Dodge Process Technology Center, have adapted techniques of parameter estimation for application to data typically resulting from metallurgical column testing. The parameterization is completed within the context of a variably saturated flow model that allows interpretation of available hydraulic information collected during hydrometallurgical column tests. A novel interpretation approach is introduced to extract the necessary hydrodynamic parameters from typical hydrometallurgical data sets. Results from the application of the approach to standard metallurgical test data will be presented together with a discussion of the application of information gained to the design and operation of a heap.

Jan 1, 2002